PORTSMOUTH — An employee of the Redhook Brewery was fatally wounded Tuesday when a pressurized beer keg exploded at the company's facility in Portsmouth.

The man was rushed to Portsmouth Regional Hospital by ambulance after he was struck in the head and chest by pieces of the keg, according to Assistant Portsmouth Fire Chief Steve Achilles.

Redhook employees found the worker unresponsive in the loading dock area at approximately 7:06 a.m., a short time after the explosion.

Achilles said the worker, who is believed to be in his 20s or early 30s, had been filling kegs with air as part of a cleaning process that removes residual beer from the kegs. He said firefighters responded within three minutes after receiving a 911 call from the employees.

The man reached Portsmouth Regional Hospital at approximately 7:30 a.m. and was pronounced dead sometime before 1 p.m., according to a hospital spokesperson.

His name has not been released.

Achilles said the explosion took place in a storage and supply area of the Redhook facility, which is located beside a brewery and pub located at Pease.

At 11:01 a.m., Redhook posted a message on its twitter account that reads, “Unfortunately, the Cataqua Pub in Portsmouth will be closed today and all Portsmouth brewery tours are canceled.”

Later in the afternoon, Andy Thomas, Redhook Brewing's vice president of commercial operations, said in a statement that the company is “doing everything in our power to understand the circumstances surrounding this tragic accident.” Smith said all non-essential operations at the brewery, including the pub, will be closed while the investigation continues.

“We believe it would not be appropriate to comment further until the investigation is concluded,” Thomas said in the statement. “Our sympathy is with his family and everyone touched by the tragedy.”

Achilles said the fire department has notified the federal Occupational Safety and Health Administration (OSHA) agency of the circumstances, and he believes OSHA will be investigating the accident. OSHA is the main federal agency charged with the enforcement of safety and health legislation.

As news spread of the industrial accident Tuesday, local brewers were surprised to learn that a pressurized keg had somehow burst apart at the Portsmouth facility.

At the nearby Shipyard Brewing Company in Portland, Maine, production manager Joseph Rank said to his knowledge, a keg has never exploded at one of Shipyard's facilities.

“I've never heard of anyone getting hurt cleaning a keg,” he said.

Kirsten Neves, managing member at Tuckerman Brewing Co. in Conway, N.H., said most breweries use high-pressure air or carbon dioxide to flush remaining liquid out of used kegs.

Neves said industrial keg cleaning systems usually have pressure regulators that would prevent such an explosion. She speculated that defects in the keg were more likely responsible for the incident.

“It's really a very tragic situation,” Neves said. “It's very, very uncommon to hear about a keg exploding like that. I've never heard of it happening.”

Dave Yarrington, director of brewing operations for Smuttynose Brewing Company in Portsmouth, concurred that most breweries use a semi-automated cleaning process for kegs, which involves purging the tanks with pressurized air.

Yarrington said Smuttynose uses a Canadian machine that allows workers to program a maximum pressure point.

Across the industry, many large-scale breweries use kegs that are fitted with so-called “Sanke valves,” which can be tapped to push CO2 through beer.

The taps can also be reversed, allowing brewers to pump water and air through the spout where beer would normally emerge from the keg.

In a semi-automated keg washing process, Yarrington said workers have the ability to load kegs onto a processing line and then monitor the operation without physically maintaining contact with the kegs.

“We haven't really heard what happened ... but you know, it'd be hard to over-pressurize these stainless steel kegs,” he said.

Tuckerman Brewing Co. President Nik Stanciu said he's personally familiar with the keg-washing line at Redhook, and is familiar with employees who have worked there in the past.

Based on the limited information released on Tuesday, Stanciu said he also suspects a physical defect in the keg might have played a role in the accident.

The man was rushed to Portsmouth Regional Hospital by ambulance after he was struck in the head and chest by pieces of the keg, according to Assistant Portsmouth Fire Chief Steve Achilles.The man, believed to be in his 20s or early 30s, was listed in critical condition after the early-morning workplace accident, Achilles said. The man's condition was unknown as of noon on Tuesday, and the Portsmouth Fire Department did not log his name, Achilles said.

Red Hook employees found the worker unresponsive in the loading dock area at approximately 7:06 a.m., a short time after the explosion.

Achilles said the worker had been filling kegs with air as part of a cleaning process that removes residual beer from the kegs. He said firefighters responded within three minutes after receiving a 911 call from the employees.

The man reached Portsmouth Regional Hospital at approximately 7:30 a.m.

Ted Lane, a spokesperson for Red Hook, confirmed a worker was injured early Tuesday, but declined further comment until the company can investigate the circumstances.

“Until we gather more information, we're not going to be able to comment further, but our hearts go out to the technician,” Lane said.

Achilles said the fire department has notified the federal Occupational Safety and Health Administration (OSHA) agency of the circumstances, and he believes OSHA will be investigating the accident.OSHA is the main federal agency charged with the enforcement of safety and health legislationAchilles said the explosion took place in a storage and supply area of the Red Hook facility, which is located beside a brewery and pub located at Pease.

Achilles said he's not aware of whether the keg was made of high-strength plastic or aluminum.At the nearby Shipyard Brewing Company in Portland, Maine, production manager Joseph Rank was unfamiliar with the idea of using air to clean kegs.

Rank said to his knowledge, a keg has never exploded at one of Shipyard's facilities.

“I've never heard of anyone getting hurt cleaning a keg,” he said.

At 11:01 a.m., Red Hook posted a message on its twitter account that reads, “Unfortunately, the Cataqua Pub in Portsmouth will be closed today and all Portsmouth brewery tours are canceled.”

At 1:51, Red Hook sent out the following statement on the tragedy:

"All,

We are saddened by the tragic event that occurred at the Portsmouth brewery this morning resulting in the death of one of our employees. Our deepest sympathies go out to his family. Out of respect for his family we are not releasing his name at this time.

We are doing everything in our power to understand the circumstances surrounding this tragic accident, and have closed down all non-essential operations at the Portsmouth brewery, including the pub, while the investigation continues.

We believe it would not be appropriate to comment further until the investigation is concluded. Our sympathy is with his family and everyone touched by the tragedy.